Saturday, 14 March 2009

Debunking The Raised Bed Myth

Debunking The Raised Bed Myth: In Defence Of Traditional Organic Methods.

For some reason it seems to be the convention these days to advise new gardeners to grow their vegetables using raised beds and/or the no dig method. This has become the new orthodoxy. The media is teeming with adverts for raised bed kits and even the soil to fill them. (I wouldn't be surprised if there's one or two in the sidebar).

I was stirred to write this piece after reading a review of the Jon Jeavons book "How To Grow More Vegetables Than You Ever Thought Possible", in which the author advocates the use of the raised bed/no dig system, or as he names it (they always have a name), bio-intensive. The reviewer (the otherwise excellent Rob Hopkins) writes as follows:


"One of the great achievements of the book is how it highlights the absurdity of many gardening practices. On a conventional allotment, the whole thing is dug over, manured, and then rows are marked out, with the plants being planted in rows as the gardener walks up and down between the rows to look after them. Sounds logical in theory, and is has been the unchallenged orthodoxy for many years. But in practice, what is happening is that you are manuring the paths as much as the beds, digging the beds and then compacting the soil in them back down again, leaving space for weeds to grow in ground you have kindly manured for them, and basically creating several rods for your own back.

In the biointensive system, the raised beds are double dug, so as to maximise the depth of root penetration, and from that point forward, compost is only added onto the tops of the beds, which are never walked on. Most plants are started first in modules or in flat trays and then planted out into the beds on the tight spacings. This means that if you plant, say, lettuces, you may need to give a light weeding after a couple of weeks, but beyond that, they grow over and make a canopy, so there is no room for weeds to grow. Brilliant.

The successful application of the biointensive mode requires a lot of compost..."


I started gardening in the eighties, after the "Good Life" boom of the seventies had petered out (to be replaced by the rapaciousness of Thatcherism, but that's another story). Allotment sites were disappearing to development at a rate of knots. I was lucky enough to get a job with the Parks Department and a couple of years later acquired my first allotment. I learnt not so much from books but from watching and learning from the old timers on the site, all of whom had plots bursting with vegetables grown using traditional organic methods. Yes, manure was delivered to the site by the trailer load and dug in at the beginning of the season and yes, they chucked on growmore as well for good measure. (Though personally I've always used blood, fish and bone). After 25 years of putting into practice what I'd learnt I think I'm starting to get the hang of it, and I'm proud to say that each year I too now have a plot bursting with fresh produce.

As one of these "absurd" gardeners I'd like to make the case for these traditional methods. (Actually I like to think of myself as a "traditional organic" rather than a "conventional" or an "absurd" gardener).

To start with, this has been the orthodoxy for many years because, I presume, our ancestors spent hundreds of years figuring it out. I think it's worth paying them some heed. Unlike us urban dwellers they spent their whole lives on the land so it's not unreasonable to think that they knew a thing or two about what they were doing. So...

"On a conventional allotment, the whole thing is dug over, manured..." I think there's a good reason for this. On any garden the soil looks static but as we know it's teeming with life - earthworms, centipedes, right down to the microscopic level with all the bacteria and so on who are busy breaking down that manure or compost and distributing it throughout the soil. All that life is moving around, no doubt some of it from one end of the plot and back again during a season. Now imagine a forest on a hundred acres and all the diversity it contains. But in a forest of only ten or even fifty acres there will likely be less diversity. Now going back to our life in the soil I would like to postulate that THE MORE SPACE IT HAS TO MOVE AROUND IN THE MORE LIFE AND DIVERSITY THERE IS LIKELY TO BE. So it follows that if you divide your plot into narrow raised beds enclosed by boards the less beneficial life you will have in your soil. I'm not a scientist so I can't prove this, it just seems like common sense.

"In the biointensive system, the raised beds...are never walked on." I've worked in gardens with raised beds and unless they are waist high then it's extremely uncomfortable trying to work on them without walking on them, or at least putting your boot on them from time to time.

"Most plants are started first in modules or in flat trays and then planted out into the beds..." Nothing new there then.

"...on the tight spacings.This means that if you plant, say, lettuces, you may need to give a light weeding after a couple of weeks, but beyond that, they grow over and make a canopy, so there is no room for weeds to grow. Brilliant." Isn't it just. Nothing new there either. I'm starting to notice a pattern here. Except for the raised bed bit this is just the same as the traditional system.

"The successful application of the biointensive mode requires a lot of compost." As in the traditional method, where it's dug in. But this is different. Here you only dig once and then in the following years you add the compost from above. Whoopee! No more digging! Unfortunatly, leaving compost on top of the soil means you lose a lot of its goodness through oxidisation. (I too use compost as a mulch once plants are growing away nicely, if I can spare it, but this is in addition to, not a substitute for, incorparating it into the soil at the start of the season).

"Companion planting" Can't argue with that, but again it's hardly a new idea.

"...the plants being planted in rows..." This is just a matter of practicality. If I had an endless supply of time on my hands I might plant in wavy rows, it might even be more aesthetically pleasing to the eye, but it'd be a bugger to plan and work round.

"...as the gardener walks up and down between the rows to look after them...compacting the soil..." Wrong. When I've not long dug over my plot and I'm sowing in the spring when the soil is still damp I work off planks so as not to compact the soil. I then don't need to walk on it again (and wow betide anyone who does) until a few weeks later when I need to start weeding. By then the top of the soil has likely settled and dried out and isn't going to be compacted because I walk backwards with my dutch hoe loosening it up. And all that life is still going on its merry way beneath my feet. I end up with blocks of plants around four feet wide, for example if I've got three rows of french beans I can reach over with my hoe to weed between the rows until the gaps has closed up and shaded out most of the weeds.

The reviewer doesn't mention watering. Raising the soil a foot above the water table inevetably means lots of watering, especially around the edges near the boards where the soil will quickly dry out. Using traditional methods once I've watered in my plants or my seed drill I NEVER NEED TO WATER, except in extreme drought conditions. One of the prime reasons for digging in manure or compost is that it holds the moisture in the soil.

Pest control: Go outside and pick up a plank that's been lying on the ground. Clinging to the underneath will be lots of slugs and snails. Now see what you have where you've got planks of wood in contact with damp soil around a raised bed.

In the traditional system I rely on hedgehogs to take care of my slug and snail problem. Around two sides of my plot is a two metre strip of blackberries where they live and I often see them trolling their way around the place of a nighttime. Now, have you ever seen a hedgehog climb up a one foot plank onto a raised bed? I think not.

Another argument often given for the raised bed system is that they warm up quicker in the spring. I'm yet to be convinced that moving the soil a foot nearer the sun will achieve this. And even if it were true it hardly outweighs the disadvantages already outlined. On top of that you've got to spend hours constructing the darn things in the first place. Probably you'll want to use recycled timber but that will rot in a couple of years of being next to damp soil. So then you'll go out and buy some pressure-treated timber or scaffolding planks and try not to worry too much about how that'll affect your carbon footprint, or what damage those heavy metals from the treatment are doing leeching into your soil. Then you're going to have to move around vast amounts of soil to fill them up. You'll have to make paths between your beds which means slabs - a lot of slabs - or imported bark with dozens of metres of weed control fabric underneath it, or hours with the strimmer. Again, I'm not a scientist but it would be interesting if someone were to do a study of the time/reward ratio of all this compared to two or three days digging once a year.

For me raised bed gardening just seems like an unnecessary complication. What's wrong with "There's the ground - go work it"? But that would be absurd. Wouldn't it?

Simon 14.3.09
This article is open source, not copyrighted, feel free to spread it around. Hopefully it might be catching. And when you're done, don't forget to compost it.

38 comments:

Jeremy Dore (GrowVeg.com) said...

Simon, I think you have some good points here. I have used both systems before and think they both have their place depending on your soil and the conditions you work in. For very heavy waterlogged soils there is a clear advantage in raised beds. By raising the soil above normal ground level it will drain better and that is why people say they warm up quicker - because dryer soil is quicker to warm up than compacted waterlogged clay! But for many other areas raising beds can, as you say, just mean that a lot more watering and maintenance must be done. I, too, have used planks to access soil without compacting it but when there are small children around I have to say from experience that raised beds really helps them appreciate which bits can be walked on and which bits are to be kept off - saving the young seedlings from being squashed. Perhaps this is partly why raised beds are so popular as there is a resurgence of interest in vegetable growing from young families?

Simon said...

Thanks for posting Jeremy, I hear what you're saying but I think that actually the reason they are used so much by people new to growing is that they have become ubiquitous in the advice given by the online gardening press who get their revenue from advertisers many of whom are flogging raised bed kits. Call me cynical - because I am!

Compostwoman said...

Simon. Good points!

I grow most of our veg in a traditional bed system BUT I also have a number of recycled plastic raised beds (made from HDPE) which I use to put my huge quantities of compost. I generate about 4000 l in spring and again in autumn, so not only to I dig it in, mulch with it BUT also use it in raised beds to grow squash, corn and courgettes as well as some early spuds.

I find it convenient, I use the full fertility of my compost and then I shovel it out in the autumn onto the veg patch ( still full of fertility...HDRA have shown it remains wonderful stuff for several years!) and then I re fil the raised bed with freshly dug out compost.

But then, I *DO* make a lot of compost ;-)

I like the fact I am closing the recycling loop by buying a recycled product. and they don't rot and can be dismantled and moved around .

But I agree that raised beds HAVE become a bit of a fad...a good idea, but just one amongst many ;-)

Anonymous said...

I have gardened around my house successfully, only to find that my daughter's physician noted that lead is around older homes...not to mention some of the things I find in my yard. My reason for a raised bed is to place soil and compost from a friend's organic farm into my yard. I just hate to drive 20 miles a day to garden.
I like your blog.

Simon said...

Thanks to you both for your comments which are very welcome as I think this subject could do with much more debate at a time when the horticultural industry is marketing raised bed kits to new growers as some kind of panacea.

Compostwoman - I am so impressed with your setup, I can see I'm going to be having a good root round in your blog especially for guidance on cider making as I always have a glut of apples which I can't even give away and end up composting. 4000 l of compost - wow, whats that in real money?

Anon - I'm blessed my plot is just through the hedge at the bottom of my garden. Thanks for liking my blog!

Compostwoman said...

Hi Simon

I use litres as a unit because I know how much a wheelbarow load is in 8o L growing medium bags....

so I use that as a guide..

not sure what the density of compost would be it would depend on how damp it was I guess?

I must admit I do make a lot...but then I have a lot of land to make it from...

well no actually its just because I am addicted to making compost..I have a professional interest and a personal passion for the stuff
;-)

Cider...there are several posts on cider, including a couple of "how to..." ones :-))

I like your blog and will add it to my blog roll, if thats ok?

Compostwoman x

Simon said...

Cheers, yes that's more than ok! I'll add yours to mine too. And thanks for all the information.

Sharon said...

Simon, I agree that the media and garden suppliers have jumped on the 'raised bed bandwagon'. I started my allotment 4 years ago and was very daunted by the prospect of digging 10 rods of very overgrown land. Marking out and then digging 8x4 beds chunked it down and made the whole thing seem more achieveable. I now have the whole plot under cultivation but only have four 8x4 beds left, the rest is open land and cultivated in the traditional way. So I can see both sides of the argument because I use both methods. I use the beds for crops that need netting protection e.g. carrots, salad etc and the larger areas for potatoes, sweet corn etc. I don't think there is any right or wrong - it's about what works for the people cultivating the plot. I would rather see fully cultivated allotments with 'raised beds' rather than an overgrown mess at risk of development.

Anonymous said...

I find your arguments to be rather shallow on several fronts.

First of raised bed and the book where around long before the modern kits.
Second, the book was designed to encourage small scale sustainable farm and medium size gardens.
Third I do not see references supporting many of you views. But the book is full of references supporting it's view points.
Fourth I do not see any comparison
To your plots production and the calculation in the chart in book.
Since production is what really matters.
Fifth I do not believe any more statements are need to debunk your shallow rant.

Anonymous said...

Sharon
production and ease of work load is what really matters.
Yes there is a right and wrong way to garden.

Simon Kirby said...

Hi Simon, I think you've made some excellent points in a fair and reasonable way. Everyone's entitled to work their allotment as they choose as long as it's not affecting anyone else, and if that's an informed choice then I won't hear anything against it, but it's my suspicion too that gardeners are being suckered in and it's right to say it.

Simon said...

Sharron - thanks for your comment; I too would rather see allotments in use no matter what method people use; my beef is with the gardening press not raised-bed gardeners!

Anon - Easy tiger, it's just a point of view! The article was a response to a review of the book, not the book itself. I haven't used any references because this was not an acedemic exercise but just me expressing my opinions based on experience and my own common sense, which may of course be different from other peoples.

Simon - thankyou - your comment cheered me up no end!


This weekend I've also invited the users of the allotments4all forum to read my post and leave their comments. You can find them here. Thanks to everyone who took the time to read the post and to those who've made a contribution to the debate.

Tee Gee - I've reproduced your comment from the forum below.

Simon said...

From Tee Gee

Hi Simon,

Tried to post on your blog but had a bit of difficulty so have copied it to here;

What is a raised bed??

As I understand it; a raised bed is somewhere between knee high and waist high not those beds with a 6 inch timber kerb around a bed of soil.

I think of the latter as just a means of keeping a plot tidy.

http://www.thegardenersalmanac.co.uk/Data/Soil-Raised%20beds/Raised%20beds.htm

Personally I think it is rather a waste of time, I would rather dig my soil deeper and improve that than put a bit of expensive timber round it.

I would say that my soil is equivalent to an 18" raised bed but I have gone down rather than up and I am quite happy with my return per square yard of produce.

This is due to single & double spit digging; http://www.thegardenersalmanac.co.uk/Data/Allotments/Double%20&%20Triple%20digging.htm

This is a typical season on my allotment; http://www.thegardenersalmanac.co.uk/Slide%20Shows/Allotment/allotment.html

I hope you don't mind my comments and like you, I respect people like dinzie's predicament of shallow soil, but I wish people would not call a bed 6" high a 'raised bed'

Perhaps "shallow bed" would be a more appropriate name to differentiate it from "deep bed" and "raised bed" gardening.

Tee Gee

Anonymous said...

Simon why post teegee post since it like her usual posts lacking in knowledge and common sense.

Simon said...

I post teegee post because she ask me to. And I think she got lots of knowledge and common sense. And I think she is a he and either way at least she got a name.

Are we done now?

mark said...

Maybe now, you should review the book "square foot gardening"

Simon said...

Maybe Mark, may be. I've got it in my sights. It's on the list. Your man Mel Whatshisface is a charlatan, sure as God made little green apples. Come the glorious day he'll be up against the wall with the rest of 'em. If someone were to be kind enough to send me a copy I'd be happy to rip it to shreds, sorry, give it my considered opinion. Square foot gardening my arse.

mark said...

simon have you checked a book store or local library to see if they have copy before you post you address so someone can send you a copy of the book square foot gardening.
To do complete review of the book I suggest you try method in the book before degrading the book.

Simon said...

Fair enough, good point, thanks Mark.

Simon said...

Comment from Lily via Facebook:

Brilliant article Simon.... I'm a professional gardener and I couldn't agree more. But then, I've never been a dedicated follower of fashion. It's a bit like the way that organic growing is lauded by many as a modern invention by the enlightened few... all of which is news to those successful gardeners in their 60's and 70's to whom chemical gardening was just a flash in the pan.

Lia Leendertz said...

Hello Simon,
This is a really interesting post and lots of food for thought. I have always fancied raised beds as i see them as making life easier, less weeding, better draining soil and, yes, just a way of keeping my allotment from descending into the chaos that always feels just a couple of slack weeks away. but i love your point about the soil organisms being isolated in little pockets, like the animals in remnants of rainforest, or something. it can't be as healthy, can it?

Simon said...

Thanks Lia, I'm glad it makes sense. I was nearly tearing my hair out last night watching Toby Buckland telling people that to grow their own veg they need to import soil, compost and scaffolding boards when all they need to do is dig up their lawns! Now, any chance of raising the debate in the guardian or is that pushing my luck?! I had another thought today on a permaculture theme (as permaculturalists always seem to use raised beds) - how many plant communities raise themselves above their neighbours or put themselves in boxes? These seem to be human traits rather than those found in nature - could it be that raised-bed advocates ate creating gardens in their own image?

Cheers, Simon

Simon said...

Oops, should have put "are" not "ate". Veg on the brain.

Lia Leendertz said...

Yes, Toby's veg planting did look like a lot of hard work didnt it? Mind you, gawd knows what their soil is like after a winter of heavy machinery. Maybe this is one case where it's justified, if only for set-dressing purposes.
It would certainly be interesting to put your points to a permaculturist, as they are usually very in tune with the needs of the soil etc... you might change their minds! As for raising this in the guardian, how would i survive without the millions i earn from the raised bed conglomerates?! will see what i can do...

Simon said...

If only Toby had explained that that was why they were doing it - and added "don't try this at home kids". The conspiracy deepens.

I've actually got quite a lot of time for permaculturalists, I like what they have to say about design and learning from nature.

I'm glad to see you've come clean about your secretive links to the timber industry. I wonder how many acres of forest will need to be felled this year so that the middle classes can grow a few salad leaves. It's never too late to turn your back on them y'know. Come on, you and me, we can rage against the machine!

Lia Leendertz said...

Well if you put it like that, how can i possibly resist?

Gwendolyn said...

I am not a fan of raised beds-- they are so often unattractive, I know of a garden with five identically sized beds edged in plastic lumber--- you might as well garden in a rubber tire for how unattractive it is.

themoderngardener said...

Although I think there are some valid (if a tad cynical) points in this discussion, I still vote for raised beds. This is mostly because we have very clay soil and find that a) it avoids us compacting the earth stepping on it, b) concentrates the manure compost in one area instead of all over including paths, c) it drains and stays warmer.

And the last point - we built our own, so we weren't pushed into it by gimmicky advertisers.

themoderngardener said...

Ps You can't urge people to grow veg at home and then rage at the middle classes when they do it their way - that's hypocritical. Celebrate that everyone is getting into your passion and hope that it does become mainstream. And I read the Guardian every day Lia!

Simon said...

Rage at the middle classes? Moi? Actually I'm raging at the horticultural "industry". (Actually just having a bit of a grump now, I've found other things to rage about).

This week I was able to invite comments on my article from readers of the US-based website Garden Rant. You can see their comments here

C4 said...

Hi Simon,

I started with a comment and ended up with a full post on my own blog. Having used both methods I find raised beds work best in my location but can totally understand how they could seem preposterous in different conditions.

I would agree that going with raised beds because the media says to do so is the wrong reason. Even so there are plenty of right reasons in my book!

Thanks for starting the discussion.

Anonymous said...

started with the "traditional" method, but I switched over to raised beds to address specific problems.

Texas has very poor soil. Specifically, it is nearly all clay. It does not drain at all. I put better dirt in the raised beds. The raised beds drain quite well (because they are raised). The new result is that that soil is "moist but well drained".

This was why I switched originally. Later I learned additional bonuses:

It was easier to get a cleaner, more "trimmed" look. I can actually take a weed-eater to the perimeter of the beds and get that "well manicured" look blends into my suburban area.

I don't track much dirt into the house when I work in the garden, because the walkways have grass between them.

I actually turn the soil over every year, as part of getting the compost worked into the soil. I don't believe that leaving it on the top is a good idea, partially because I get some mushrooms when I do, and partially because the sun, atmosphere degrades the compost, and partially because the whole soil needs the benefit, not just the top.

What I would say to any "traditionalist" is that, you are right, we are not that different. Just imagine a few changes to your methods.

First, we put grass or gravel down the rows, for a more pleasant browsing experience, more like pathways. Now we make them a little wider, so you can sit down easily, not hunch over.

Well, the grass grows into the rows, that's no good. So we put a barrier, to separate the path. Just like in a flower bed.

Now we widen the row a little, so that the wider path doesn't cost us way too much space efficiency. Not so wide that we can't reach across the row easily though. Maybe 2 "rows" worth of plants per "bed"...

Now we are basically a raised bed, aren't we? It's just not that different. It's a "traditional" garden, just with more finished "paths". Except the beds can be any shape, and they become a landscape element that you can be creative with, like a koi pond, or a stone pathway, or a bench.

Enjoy the outdoors!

Simon said...

Thanks to you both for your comments, it's been quite an education finding out how other people do things.

David said...

Simon, an interesting and thought provoking topic. This is my forth year growing vegetables so I’m still a bit of a novice. I was completely clueless when I started gardening, I knew nothing about fads or fashions, indeed, I knew nothing about horticulture at all. In four years I’ve learned from books, the internet, family and friends and of course, trial and error.

When I initially began digging my wild and badly neglected garden, I discovered fibrous pine tree roots stretching 3 - 4 metres under the boundary wall. My neighbours damn trees spoiling nearly half my plot. A friend recommended raised beds so I did a little research and built six beds measuring 6’ x 3’ and about 6’’ in height. I’ve used slabs in between each bed for easy access.

There are pros and cons in every system and I guess it comes down to personal taste. For the most part, I found the raised beds a good way to grow veg. I like the no digging, the easy access for planting and weeding etc. The downside for me is the plague of woodlouse and other bugs the wood attracts. Not to mention the endless and tiresome debates about using treated or untreated wood. On some websites they go on and on ad nauseam. So after reading your article, I’ve decided to keep two raised beds where the tree roots are prolific and to dismantle the other four at the end of the growing season. Next year I’ll try my hand at the more traditional method and see how it works out.

Simon said...

Thanks for your comment David. I'd be interested to hear how it turns out for you next year.

mark said...

Hi there Simon, I relaly like your blog and it seems like there is alot of nice good tips and hints for allotments. I thought you may like this link to our gardening site, BulldogHandTools.co.uk
It may be of use for your readers and perhaps yourself?!?

Thank and keep up the good work

wingedshadowwolf said...

Well I have to agree with you on the point of it seeming like the marketing "pros" took raised beds(square foot gardening too) and turned it into a fad. As someone with clay and gravel for soil, it's a very practical way of gardening. I own a copy of Mel's book, I think it might be the only garden book i own. I get lots of info from the library and the internet as well. I also say don't knock it till you've read it. I found the intro interesting. It was his way of the rebelling against the thought pattern of "it's what everyone is doing" almost from the opposite side of the board from your argument. Actually a few comments from the bottom of this blog page, the Anon from Texas basically described Mel's garden bed idea. I actually came over to this blog from one on wood treatment since i would like to plant things in(on) the ground this year instead of in pots on the porch! I've also got to fix my crumbling greenhouse. Happy Gardening!

Anonymous said...

I use a combination of traditional allotment gardening and have built a few raised beds which I have filled with topsoil/compost. Why? Because my parsnips, carrots etc grow straighter in a deep, cleaner, stone/lump free soil. Also by using raised beds, I reduce the prospects of attacks by carrot flies.They ARE more labour intensive, for all the reasons previously discussed but at least my carrots are straight!